There is a disquieting reason Ruth Bader Ginsburg's defenders have been denying, however implausibly, the clear meaning of the Supreme Court justice's recent remarks about the history of abortion law, and that reason is this: Historically, eugenics has always been a significant component of the intellectual underpinnings – and political impetus – of the movement to legalize abortion.

This legacy is glossed over by the rhetoric of today's "pro-choice" tacticians, who couch their arguments almost exclusively as a question of a woman's inalienable right to control her body and to make her own reproductive decisions. This reasoning carried the day, at least with the U.S. Supreme Court, which rendered it a constitutional right. But, from the early days of the national discourse on this topic, the idea of feminist empowerment was coupled with the less noble rationale of eugenics, that disturbing dogma that seeks to improve the human race through selective mating – and by controlling who has the opportunity to be born.

Ginsburg rekindled this ancient memory, and not inadvertently, in an interview with journalist and lawyer Emily Bazelon that was published in The New York Times Sunday magazine on July 7. Bazelon's colleague, Hanna Rosin, touted the interview the day before, writing on her blog, "Our own Emily has a fantastic and revealing Q & A with Justice Ruth Bader Ginsburg." That word "revealing" proved to be quite an understatement.

In case you missed it, the relevant quote came while the two women were discussing the history of jurisprudence that came after Roe v. Wade. Despite some concern that poor women would be pressured into having abortions, the case law worked out the other way. In 1977, the Supreme Court ruled that states were under no obligation to fund abortions, and in a 5-4 1980 decision, Harris v. McRae, the high court upheld a congressional ban against using Medicaid funds for abortion.

"Yes, the ruling about that surprised me," Ginsburg told Bazelon. "Frankly, I had thought that at the time Roe was decided, there was concern about population growth and particularly growth in populations that we don't want to have too many of. So that Roe was going to be then set up for Medicaid funding for abortion. Which some people felt would risk coercing women into having abortions when they didn't really want them. But when the court decided McRae, the case came out the other way. And then I realized that my perception of it had been altogether wrong."

Melinda Henneberger, my Politics Daily colleague, wrote about this interview on Friday, skeptically relaying Bazelon's claim that Justice Ginsburg didn't really mean the words "populations that we don't want to have too many of" -- or, rather, that the pronoun "we" meant other people, not Ginsburg herself. As you can see from her post, Bazelon's explanation struck Melinda as willfully obtuse. But this is hardly the first time prominent pro-choicers have had to engage in semantic gymnastics to obscure a longtime underlying rationale for their position that is neither politically nor morally correct.

In the early part of the 20th century, pioneers in the birth control movement routinely cited poverty, disease, physical disability, mental acuity, and even racial heritage as reasons to support their cause. In her 1922 book, "The Pivot of Civilization," Margaret Sanger, the founder of the American Birth Control League, an organization that would become Planned Parenthood, opens Chapter 4 with this salvo: "There is but one practical and feasible program in handling the great problem of the feeble-minded. That is, as the best authorities are agreed, to prevent the birth of those who would transmit imbecility to their descendants."

Chapter 4 of that manifesto is actually titled "The Fertility of the Feeble-Minded," and in it, Sanger goes on with some passion about the cascading societal problems caused by those with "feeble" minds, by which she seems to mean those with lower-than-average IQs, persons otherwise identified as "morons" "imbeciles" and "mental defectives."

"We do not want word to go out that we want to exterminate the Negro population if it ever occurs to any of their more rebellious members." - Margaret Sanger

It appears on close reading that she isn't necessarily talking only about those with mental disabilities, but also about uneducated members of what sociologists today call the underclass. And who will identify such persons, and coerce them, presumably, to submit to forced sterilization? Well, Sanger quotes approvingly from a doctor of that era named Walter E. Fernald, who wrote:

"We now have state commissions for controlling the gipsy-moth and the boll weevil, the foot-and-mouth disease, and for protecting the shell-fish and wild game, but we have no commission which even attempts to modify or control the vast moral and economic forces represented by the feeble-minded persons at large in the community."

Race is inevitably entwined in such remarks, for Sanger goes on to regale her readers about a case study of a "feeble-minded girl, twenty years of age" who was the product of a teen mother and who lived in a "thickly populated Negro district" before being apprehended for solicitation of prostitution. The author dismisses as naïve "some of our doctors" who believe that "there is a place for the good feeble-minded," by which she seems to be saying those who are merely a little below average in intelligence – the kind of person whom she fears "may be encouraged by church and state to increase and multiply until he dominates and gives the prevailing 'color' – culturally speaking – to an entire community."

Now, Sanger herself was certainly not racist in her personal dealings with African-Americans, and she didn't countenance those who were. She counted as allies in her cause of making contraception available to Southern blacks many of the leading black intellectuals of her time. Yet many of the white elites who funded her cause were indeed racist, as well as proponents of a harsh version of eugenics when it came to the disabled, and she deftly played on these sentiments while building support for her cause.

In 1939, Sanger collaborated with two other women on a report called "Birth Control and the Negro," which asserted that "negroes present the great problem of the South." The paper sketched out the broad details of a birth control program aimed at a mostly illiterate population that "still breed carelessly and disastrously." To this day, Planned Parenthood officials will point out that this line was borrowed from a 1932 Birth Control Review article by black radical W.E.B. DuBois. But Sanger's apologists are harder-pressed to justify the wording of a letter she wrote in December of that year to Proctor & Gamble heir Clarence Gamble, proposing that money be allocated to train "an up and doing modern minister, colored, and an up and doing modern colored medical man" to tour the South preaching the need for birth control. "We do not want word to go out that we want to exterminate the Negro population and the minister is the man who can straighten out that idea if it ever occurs to any of their more rebellious members."

This passage is a favorite of modern Christian conservatives seeking to discredit Planned Parenthood, but in a previous time, it was employed to great effect by black activists. Radical professor Angela Davis quoted the provocative wording in her 1983 book, saying the Negro Project "confirmed the ideological victory of the racism associated with eugenic ideas." A decade earlier, a certain "up and doing" black preacher drew on the same material in rejecting legalized abortion as little more than "black genocide." His name was Jesse Louis Jackson.

Jackson's mother was undoubtedly the kind of woman Margaret Sanger had in mind when she proposed raising the quality of life for Southern blacks by aggressively pushing birth control in that part of the country. Sanger was hardly alone. In the 1970s, Jackson would often refer to the circumstances of his own birth: "I was born out of wedlock," he once wrote, "and against the advice that my mother received from her doctor, and therefore abortion is a personal issue for me."

In 1977, Jackson penned an essay for the National Right to Life News in which he called abortion The Question – the italics were his – of the 20th century. He meant ending abortion. "Human beings cannot give or create life by themselves, it is really a gift from God," Jackson wrote. "Therefore, one does not have the right to take away (through abortion) that which he does not have the ability to give."

In those days, Jackson sent an "Open Letter to Congress" in which he asserted flatly "as a matter of conscience I must oppose the use of federal funds for a policy of killing infants." He was a featured speaker at the 1977 March for Life, where he posed this searing question: "What happens . . . to the moral fabric of a nation that accepts the aborting of the life of a baby without a pang of conscience?"

It's a question those in the right-to-life movement are still asking, even if Jesse Jackson is not, as the exigencies of political ambition robbed the right-to-lifers of one of their most passionate and inspiring voices. By the mid-1980s, when Jackson was indulging himself with visions of a black politician from Chicago entering the White House – himself, not Barack Obama – he switched sides in this great debate. He said all the right things, this newly indoctrinated national Democrat, but it didn't sound quite as persuasive.

The new Jesse Jackson said that abortion is acceptable because "it is not right to impose private, religious and moral positions on public policy." The old Jesse Jackson maintained: "If one accepts the position that life is private, and therefore you have the right to do with it as you please, one must also accept the conclusion of that logic. That was the premise of slavery. You could not protest the existence or treatment of slaves on the plantation because that was private."

This intellectual migration is apparently one that Democrats with dreams of national office must make. It's a journey taken by Dick Gephardt, Al Gore, and Bill Clinton as well. Occasionally, it happens the other way, too. George H.W. Bush was for abortion rights before he was against them. He seems to have changed position in a matter of hours, when Ronald Reagan offered him the vice presidency. (Previously, Bush and his wife had been contributors to Planned Parenthood; his father had served on its board.)

If politicians feel constrained from talking about this issue honestly, federal judges with their lifetime appointments need not. Thus, Ruth Ginsburg let her guard down apparently, resulting in her "Michael Kinsley moment" – committing a gaffe by speaking the truth. If her defenders want to brush away that truth, well, that's part of the famous Kinsley formulation, too. Yet, the underlying themes Ginsburg invoked are still present, and one doesn't have to go back to Margaret Sanger or 1939 to find them:

In 1991, the state of Maryland passed an abortion law billed as a safety net in case the Supreme Court overturned Roe. Seven months after President George H.W. Bush signed the American With Disabilities Act, this Maryland statute prohibited the state from interfering -- at any stage -- with a woman's decision to terminate a pregnancy if "the fetus is affected by genetic defect or serious deformity or abnormality." This is a pretty good working definition of eugenics. So, too, was the ugly talk directed in the last presidential campaign against the mother of a baby boy with Down syndrome, as are the statistics showing that blacks have hugely disproportionate numbers of abortions in this country year after year.

In other words, Ruth Ginsburg's fears that poor people cannot avail themselves of the rights conveyed by Roe appear to be unfounded. Could it be that Margaret Sanger's vision – the part we don't really want to think about – has come to pass?